Grinding machine



April 23, 1935. w. D. ARCHEA GRINDING MACHINE Filed Feb. 3, 1933 4Shgets-Shget (Halter D. Avchea m Maw April 23,1935. w. D. ARCHEA1,998,603

- GQINDING MACHINE Filed Feb. 3, 1953 4 Sheets-Sheet 2 F v wf Siwi lz/hw [Ualter D. Archer:

Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE The Heald .MachlneCompany,

Worcester,

Mass, a corporation of Massachusetts Application February 3, 1933,Serial No. 655,069

11 Claims.

The present invention relates to grinding machines and particularly to asurface grinder for use especially in the grinding of the faces ofdiscshaped articles such as clutch discs and the like.

In prior devices of this character. the grinding wheel is moved into andout of operative position and the relative feeding movement of theworkpiece is procured either manually or in certain cases at apredetermined constant rate by me' chanically controlled mechanism. Oneof the principal objects of the present invention is to provide afeeding movement which advances the workpiece toward the grinding wheelat a constantly diminishing rate. In this manner. the grinding operationbegins with a relatively coarse feed and is gradually reduced to a veryfine or slow feed which results in a smooth polished surface. I

A further feature of the invention resides in the provision of a machineof the surface grinder type, the cycle of which is automaticallycontrolled. the machine being brought to rest at the completion of agrinding operation. In this machine, the grinding operation isdiscontinued in response to rotation of the workpiece or the workholdingmember in which the workpiece is mounted.

Other objects and advantages of the invention will more fully appearfrom the following detailed description taken in connection with theaccompanying drawings in which:-

Fig. i is a front elevation of a machine embodyingthe invention.

Fig. 2 is a plan view of the machine of 'Fig. 1.

Fig. 3 is a vertical section along the line 3-3 of Fig. 2, showing theconstruction of the workholder. r

Fig. 4 is a vertical section along the line 4-4 of Fig. 3 showing thedriving mechanism for the workholder.

Fig. 5 is a vertical section along the line 3-4 of Fig. 4.

Fig. 6 is an enlarged fragmentary view of-the clutch and brake unitshown in Fig. 4.

v Fig. 7 is a vertical section substantially along the line 'I-'i ofFig. 2.

Fig. 8 is an enlarged detail of the structure of Fig. 7 as viewed alongthe line 8-8 of this figure.

Fig. 9 is a sectional view along the line' 9-9 of Fig. 'I.

Fig. 10 is a vertical section substantially along the line lliill ofFig. 7 showing the fluid pressure mechanism for actuating the workhead.

Fig. 11 is a vertical section along the line I l-i I of Fig. 1.

Fig. 12 is a vertical section along the line l2-l2 of Fig. 11 showingthe control valve for the workhead. i

Fig. 13 is a section along the line l3l3 of Fi 12.

Fig. 14 is a section along the line l4--l4 of Fig. 13.

Fig. 15 is a detailed section along the line l5-I5 of Fi 12.

Fig. 16 is a fluid pressure diagram. 10

Like reference characters refer to like parts in the different figures.

Referring to Figs. 1 and 2, the machine comprises a base i on which ismounted a housing 2 for agrinding wheel 3, the spindle of which is 15Journaled in horizontal bearings I also mounted on the base. The basealso provides ways 5, see Figs. 4 and 11. on which a table or carriage 6is horizontally movable toward or away from the grinding wheel andperpendicularly to the axis 20 thereof. The carriage 8 has. as anintegral part thereof, a workhe'ad or housing I which provides a supportfor a rotary workholder 8 in which a workpiece a. is mounted. Saidworkpiece, which is shown as a disc having an annular fiat surface to beground, is positioned with thesurface to be ground in opposed relationto the periphery of the grinding wheel and the latter, as will beapparent. is at least as wide as the width of the annular surface of theworkpiece between the inner and outer edges thereof in order that thewheel may grind over the entire width of the surface 01 the workpiecewithout a reciprocatory traverse of said wheel.

Referring now to Fig. 3, the workholder 8 is 85 carried on the end of ahollow spindle 8 which is ioumaled in bearings 10 provided by thehousing I. A worm gear ii is secured against rotation and against axialmovement on said spindle and is in engagement with a worm I! carried by40 a shaft l3 journaled as shown in Fig. 4 in the housing 1. Said shaftI! is connected through a clutch and brake mechanism i4. shown in detailin Fig. 6 and hereinafter more fully described. to a pulley i 5 in ahousing It secured to the hcusing Said pulley i5 is connected by asuitable belt H to a pulley IE on the shaft of a driving motor It, saidbelt l1 and pulley l8 being also mounted in the housing It.

A draw rod 20 is longitudinally slidable in the hollow spindle 9 and isconnected in any suitable manner to the jaws ii of the work-supportingmember or workholder 8. the latter being of any desired type in which amovement of the draw rod to the right, Fig. 3, operates to close thejaws for clamping a workpiece therein, and movement of said draw rod tothe left operates to open the jaws for releasing the workpiece. Foractuation of the draw rod 20, the spindle 9 carries a flange 22 on theright hand end thereof, and said flange has secured thereto a cylinder23 in which a piston 24 is slidable, said piston being connected by apistonrod 25 to the end of the draw rod 20. Fluid under pressure isadmitted selectively to opposite sides of the piston for opening orclosing of the jaws of the workholder.

Referring now to Fig. 16, fluid under pressure is supplied by a pump 26which draws fluid from a tank 21 in'the base of the machine. From thepump, fluid under pressure is conducted by a pipe 28 to an inlet port 30in a valve casing 3|, the latter being positioned on the front of themachine, as shown in Fig. 1. Said casing is provided with an exhaustport 32 connected by a conduit 33 to the tank and is also provided withoutlet ports 34 and 35 connected by pipes on either side of the piston.The jaws of the workholder may thus be opened or closed as desired bymovement of the lever 46 which, as willv be apparent, is accessible onthe front of the machine.

As above stated, the hollow work-supporting spindle 9 is brought to restor set in rotation by actuation of the clutch and brake mechanism |4without stopping the driving motor l9. Referring now to Fig. 6, in whichthis mechanism is shown in detail, the shaft l3 by which the spindle 9is rotated is recessed at one end thereof to provide a journal for theleft hand end of the shaft 4| on which the pulley I5 is mounted, saidshaft 4| being journaled in the housing 1 in axial alinement with theshaft l3. The shaft 3 has secured thereto a member 42 adjacent the righthand end thereof and within the opening 43 provided in the housing I forthe clutch and brake mechanism. Said member 42 has a plurality ofprojecting pins 44 which extend parallel to the axis of the shaft l3 andprovide a support for an annular friction or clutch disc 45, the latterbeing axially slidable on said pins.

The end of the shaft 4| adjacent the end of the shaft l3 has a member 46secured against rotation thereon and the member 46 provides an annularsurface 41 on which a pair of annular friction or clutch discs 48 and 49are longitudinally slidable and supported against rotation thereon. Saidmember 46 also provides a-plurality of bell crank levers 50 mounted inslots provided by said member and pivoted on pins 6| therein. One end ofsaid bell crank levers engages the outer of the two friction discs 46and 49 for urging said discs toward each other and into engagement withthe friction disc 45 which is positioned between them to preventrelative rotation between said disc 45 and the other discs to procure inresponse to rotation of the member 46 a corresponding rotation of theshaft l3.

The member .48 providm a shoulder 5| against.

which the friction discs are urged by the bell crank levers, saidshoulder preventing movement of said discs to the right.

An actuating member 52 for the bell crank levers 50 which is slidablymounted on the shaft 4| and secured against rotation thereon has anannular cam-shaped surface 53 for engagement with the free ends of thebell crank levers 56 for supporting said levers in the position shownwith the friction discs in positive driving engagement. Movement of theactuating member 52 to the right from the position shown releases thebell crank levers to permit separation of the several friction discs,thereby breaking the drive connection between the shaft 4| and the shaft|3 so that the latter may be brought to rest. Movement of the member 52to the left reengages the clutch disc to procure rotation of the shaftl3 and accordingly rotation of the workholder 8.

The actuating member 52 is provided with an integral annular flange 54on which a grooved ring 55 is rotatably mounted, said ring being splitto permit mounting of the latter upon said flange. Said ring 55 isprovided with projecting pins 56. in diametrically opposed relation andsaid pins are received in notches 51 in the ends of a bifurcated member58 which is mounted on the lower end of a rod 59. The latter is providedwith an enlarged spherical portion 60 which is journaled in a coverplate 6| suitably secured over an opening 62 in the housing I, saidspherical portion providing for rocking movement of said shaft.

Referring now to Fig. 4, the upwardly projecting end of the rod 59beyond the spherical portion 60 has secured thereto a U-shaped member63, the ends of which are provided with alined openings for thereception of a pin 64 carried by the end of a rod 65. The latter formsan extension of a piston rod 66 projecting from a piston 61 which ismovable in a cylinder 68 mounted on the housing I and which is actuatedin response to fluid under pressure admitted selectively to the cylinderon either side of the piston. Movement of the piston 61 to the leftprocures a corresponding movement of the actuating member 52, Fig. 6, tothe right to separate the clutch discs, and movement of said piston tothe right procures, through movement of the. member 52 to the left,reengagement of said clutch discs, thereby procuring rotation of theworkholder 8 in response to-rotation of the shaft 4|.

When the connection between the shafts l3 and 4| is broken, theworkholding member 8 is brought to rest by a brake mechanism, theconstruction of which is best shown in Figs. 5 and 6. Referring to thesefigures, the member 42 which, as above stated, is secured to the end ofthe shaft I3, is provided with a, cylindrical surface 10 which isencircled by a brake band II. The opposite ends of said brake band areprovided with suitable lugs 12 and 13 through which a rod 14 projects,said lugs being urged apart by a spring 15 which encircles said rod. Oneend of said rod 14 is slidable in a sleeve 16 secured in-the housing Iand the opposite end of said rod is slidable in a cap 11 forming one endof a cylinder I8 in which a piston 80 secured to the end of said rod 14ismovable, said cylinder being suitably secured to the housing I. Therod I4 carries a collar 6| adjustable thereon and in a position toengage with the lug 13 during movement of said rod to the left, Fig. 5.The opposite lug 12 engages the end of the sleeve 15 so that a movementof the rod I4 to the left tightens the brake band around the surface 18to bring the shaft I8 and accordingly the workholder 8 to rest. Movementof said rod 14 to the right from the braking position releasesthe lug 18and the spring 18 procures separation of the lugs 12 and 13 to releasethe brake band. Shifting movement of the rod 14 is procured by admissionof fluid under pressure selectively to the cylinder 18 on opposite sidesof the piston 88, as will be pointed out hereinafter, for shifting ofsaid piston to one end or the other of the cylinder, thereby procuring9. corresponding movement of the rod 14 secured thereto.

With a workpiece a mounted in the workholder 8 and rotated from thedriving motor I8, a movement of the workhead to the left, Fig. 1, isprocured by fluid under pressure for a movement of the workpiece intogrinding position and for a feeding movement of said workpiece againstthe grinding wheel, said movements being procured by movement of thetable 8 on which the workhead is mounted. Referring particularly to Fig.'I, the housing 1, of which the table Ii is a part, has secured theretoa housing 82 in which an internally threaded sleeve 88 is journaled, thelatter being supported against axial movement in said housing. Saidsleeve 88 receives a threaded rod 84, the right hand end of which isprovided with a' U-shaped member 85 secured thereto by a set screw 88.The ends of said member 85 are connected by, and provide a support for,a pin 81 on which one end of a link 88 is pivotally mounted, Theopposite end of said link 88 is mounted on a pin 88 carried by anenlarged portion SI of a shaft 82 (see Fig. 10) journaled in a bracket83 which is secured by bolts 84 to the base-of the machine. The pin 88is eccentric' to the axis of the shaft 82 so that turning movement ofsaid shaft procures a longitudinal movement of the member 88 andcorresponding feeding movement of the housing 1 to the left.

Rotation of the shaft 82 is procured in response to fluid underpressure. Referring to Figs. 7 and 18, the shaft 82 carries, at the endremote from the enlarged portion 8i, a gear 85 secured against removaland against rotation on said shaft by a nut 88. Said gear which ispositioned withina recess 81 in the bracket 88 engages a rack 88verticallymovable in a bore I88 provided in said bracket. Said rack 88is secured to and forms an extension of a piston rod IN and the lowerend of the latter is secured to a piston I82 in a cylinder I88 securedto the bracket 83. The piston rod I8I just above the piston I82 isprovided with an enlarged cylindrical portion I84 and a projectingportion I85 on the lower end of said rod extends a short distance belowthe piston; 'said portions I84 and I88 control the rate of movement ofthe piston within the cylinder as will hereinafter appear.

Fluid under pressure is admitted to either end of the cylinder above orbelow the piston to procure movement of the same for actuating the:workhead. As'the piston mcfves upwardly in response to fluid underpressure entering below the piston, the rack is moved upwardlytherewith,

procuring a turning movement of the shaft 82 (as seen in .Fig. 7) andcorresponding longitudinal movement of the workhead 1 toward thegrinding wheel to ladvance the workpiece into grinding position and tofeed the workpiece against the grinding wheel when in grinding position.The workpiece is withdrawn from the grinding wheel during the downwardmovement of the piston to provide for removal of thecompleted workpiece'bore II8 connecting said horizontal channel to and positioning of anunground workpiece in the workholding member 8. As will be pointed outhereinafter, the crank motion for feeding the workpiece against thegrinding wheel results in a rapid feeding movement at the beginning ofthe grinding operation which is gradually reduced during that operationuntil, in the forward position of the carriage which supports theworkpiece, there is no forward feed and a very smooth finish isaccordingly produced on the workpiece.

The movements of the piston I82 are under the control of valves bestshown in Fig. 10. Referring to this figure, the cylinder head I88 at theupper end of the cylinder I88 is providedwith a horizontal channel I81which extends from an inlet port I88 and intersects a verticalcylindrical bore I88 surrounding the piston rod. Said bore is of,"

valve III provided in said horizontal channel. 5

An additional vertical bore H2 is provided in the cylinder head I88 andintersects the horizontal channel I81. The bore H2 is provided with asuitable check valve II8, the latter being, for example, in the form ofa ball urged against the valve seat by a spring, said valve being ofwellknown construction. The check valve H3 is positioned to permit freepassage of fluid into the cylinder during downward movement of thepiston and to prevent exhaust of fluid through said bore II2 duringupward movement of said pis ton. The lower cylinder head II4 for thecylinder I88 is similarly provided with a port II! from which extends ahorizontal channel H8 intersected by a vertical bore II1 which is of theproper size and in a position to receive the projecting end I88 of thepiston red as the piston approaches the lower limit of movement. Saidhorizontal channel I I8 is also intersected by a vertical the interiorof the cylinder, and the fluid supply through said vertical bore islimited by a needle valve I28 similar to the valve III and of anysuitable construction. An additional vertical bore I2I which intersectsthe horizontal channel is provided with a check valve' I22 similar 'tothe check valve I I3. The check valve I22 is arranged to prevent exhaustof fluid'through the bore I2I from within the cylinder, althoughadmitting fluid freely into the cylinder during upward'movement of thepiston.

As fluid enters the cylinder I88 beneath the piston I82 for advancingthe workpiece toward the grinding wheel, the piston moves upwardly tothe position shown in Fig. 10 at a rapid rate. fluid being admittedfreely to said cylinder past the check valve I22. As soon as the pistonis advanced far enough to withdraw the projecting end I85 of the pistonrod from the vertical bore II1, the fluid under pressure may enterthrough said vertical bore for procuring a continued up-- ward movementof the piston. At the same time, fluid from above the pistonexhauststhrough the vertical bore I88 surrounding the piston rod so thatthe exhaust of fluid is unthrottled.

The rapid movement of the piston upwardly procures a rapid advance ofthe workpiece from inoperative position into operative or grindingposition andthis movement would, if not suitably checked, cause theworkpiece to engage the grind- .operation on the workpiece.

ing wheel too rapidly. To avoid this condition, the rate of movement ofthe workpiece toward the grinding wheel is materially reduced just asthe workpiece comes into contact with said wheel. At this point in theadvancing movement of the workpiece, the piston is approaching the upperend of its movement. Just before the workpiece engages the grindingwheel, the enlarged portion I04 enters and closes the'vertical bore I08so that further exhaust of fluid from above the piston during theremainder of the upward movement of said piston occurs at a very slowrate past the needle valve, escape of fluid through the bore II2 beingprevented by the check valve. This material reduction in the rate ofexhaust of fluid from the cylinder causes the piston to travel at a veryreduced rate of speed during the remainder of its upward movement for aslow feeding movement of the workpiece against the grinding wheel. Thecrank motion by which the movement of the workhead is procured inresponse to the rotation of the shaft 82 results in a constantlydiminishing rate of feed in response to the movement of the piston at auniform rate. The feeding movement of the workhead is discontinued whenthe piston reaches the upper end of its movement at which time theeccentric pin 90 is in horizontal alinement with the shaft 92 andtheworkhead remains in the forward position with the workpiece inengagement with the grinding wheel for a short period in order toprocure a finish grinding The workhead is then retracted intoinoperative position at a rapid rate, as will hereinafter appear.-

Upon reversal of the flow of fluid to the cylinder I03 the piston I02moves downwardly to withdraw the grinding wheel from the work piece.

The movement of said piston occurs at a relatively rapid rate, the fluidfrom beneath the piston exhausting through the bore I "until the pistonapproaches the end of its downward movement. At this time, theprojecting end I05 of the piston rod enters and closes the vertical boreIII to prevent further exhaust of fluid through said bore, the fluidthereafter exhausting slowly past the needle valve I 20 so that theremaining downward movement of the piston is procured at a relativelyslow rate. The workhead is thus brought to rest in inoperative positionwhen the piston reaches the lower end of its movement without anyexcessive jarring of the parts which would occur if the rate of movementof the piston were not decreased.

The workholding member 8 is set in rotation at the beginning of theforward movement of the workpiece toward the grinding wheel. Referringnow to Fig. 16, the admission and exhaust of fluid under pressure to andfrom the clutch cylinder, the brake cylinder, and the work-feedingcylinder is controlled by a single valve I23 in a casing I24. During themovement of the -workpiece toward the grinding wheel the valve I23 isheld in the left hand position shown by a latch I25 against the tensionof a spring I26. An inlet port I21 in the valve casing I24 is connectedby a conduit I28 to the pressure side of the pump, and exhaust ports I30and I3I in said casing are connected by conduits I32 and I33 to the tank21. An outlet port I34 in said casing is connected by a conduit I35 tothe left hand end of the clutch cylinder 68 and byconduits I36 and I3Ito the left hand end of the brake cylinder I8 and to the lower end ofthe work-advancing cylinder I03 respectively. Another outlet port I38 isconnected by leads I40, I and I42 to the right hand end of the clutchcylinders, the right hand endof the brake cylinder and the upper end ofthe wdrkfeeding cylinder respectively.

With the. valve I23 in the position shown, fluid under pressure isadmitted to the left hand end of the brake cylinder I8 for shifting thepiston 80 therein to the right, thereby releasing the brake to permitrotation of the work-supporting member. At the same time, fluid underpressure is admitted to the left hand end of the clutch cylinder 68 toprocure engagement of the clutch discs and thereby to cause rotation ofthe worksupporting member. Fluid under pressure is also admitted at thistime to the under side of the work-advancing piston I02 for advancingthe workpiece from inoperative position into operative relation to thegrinding wheel and for a feeding movement of said workpiece against thewheel.

The valve I23 is supported in the left hand position shown for apredetermined period and is then released from the latch for movement toits right hand position under the influence of the spring I26. In thisposition of the valve, fluid under pressure is directed to the righthand ends of the clutch and brake cylinders and to the upper end of thework-advancing cylinder for retracting the workpiece from the grindingwheel, for disengaging the clutch discs, and for bringing theworkholding member to rest. The valve I23 in its right hand positionalso connects the opposite ends of said cylinders to the exhaust port ofthe casing I24 to permit discharge of fluid from within said cylinders.

The grinding operation is controlled by the rotation of the workholdingmember, and after a predetermined rotation thereof, the above notedvalve I23 is automatically shifted to the right hand end position tobring the grinding operation to a close. Referring now to Fig. 3, thespindle 9 for the work-supporting member 8 has a sleeve I43 securedagainst rotation thereon and provided with gear teeth I44 engaging withsimilarly formed teeth on a gear I45 keyed to a shaft I46 journaled, asshown in Fig. 11, in bearings I4'I secured in the workhead. Said shaftI46 has an enlarged end I48 remote from the gear I45 and this end isprovided with a slot I50 for the reception of a tongue I5I formed on theend of a shaft I52 joumaled in a housing. I53 which is secured to theworkhead. The shaft I 52 carries a worm I54, Fig. 12, which engages witha worm gear I55 carried by a shaft I56 also journaled in the housingI53. I An annular member I5'I surrounds said shaft I56 and is secured tothe worm gear I55 by bolts I58 for rotation therewith. One end of saidannular member I51 provides a star wheel I60 (Fig. 13) for engagementwith one end of a plunger I6I longitudinally slidable in a bearing I62provided by a cap I63 secured to the housing I53. A threaded rod I64engages a threaded bore in the end of said plunger I6I and carries onthe outer end thereof a projecting arm I65 which is secured againstrotation on said rod. The plunger I6I is held against rotation in thebearing I62 by a suitable key and thus supports the arm I65 in aposition for engagement with the projecting arm I66 of a member I61secured against rotation on a shaft I68 by a set screw I10, said shaftbeing journaled in the housing I 53.

As shown in Fig. 14, the end of the shaft I68 remote from the member'I6Ihas an enlarged valve I28 is held in the left hand position shown. Thus,as the star wheel I88 is rotated, in response to the rotation of thework-supporting member, to carry a point of said wheel beneath the endof a plunger i8 I, said star wheel shifts the plunger to the left torock the shaft I88 and thereby withdraw the iach I25 from the collar I18on the valve I23 with which the latch engages. As the latch iswithdrawn, the valve I28 is shifted by the spring I26 into its righthand position, thereby withdrawing the workhead from grinding positionand stopping rotation of the workholding member. 'The control valve I28has a projecting stem I14, Fig. 12, provided with spaced collars I18 forthe reception of a pin I18 carried on the end of an arm I11. The latteris secured against rotation on the inner end of a shaft I18 journaled inthe workhead (see Fig. 11), and the forward endof said shaft projectsbeyond the forward surface of the workhead and carries an upwardlyextending lever I88 by which said valve'may be manually shifted to theleft for starting a grinding operation.

During the grinding operation, the pressure of the grinding wheelagainst the workpiece exerts an axial thrust on the workholding memberand, as shown in Fig. 3, the worm gear II, which is secured to'thespindle 8, is provided with a flat annular surface I8I for engagementwith a wear ring I82 secured, as by pins I88, to a portion of theworkhead to prevent axial shifting of the spindle within said workhead.

To compensate for the reduction of the diameter of the grinding wheelresulting from wear thereon, as well as from dressing operations bywhich the surface is maintained in proper cutting position, the positionof the carriage relative to the advancing mechanism is shifted by amechanism best shown in Figs. 7 and 9. Referring to these figures, thesleeve 88 which, as above stated, is journaled in the housing 82, isprovided with an integrally formed worm gear I84 which isengaged by aworm I88 mounted on a shaft 188, the latter being journaled in thehousing 82. Said shaft is held against longitudinal movement in thehousing 82 by collars I81 and I88, Fig. 9, secured in spaced relation tosaid shaft and engaging the housing 82. One end of said shaft I88projects beyond the housing and has a hand wheel K90 secured thereto,the latter having a handle I9I by which to procure rotation of the wormI88 and corresponding rotation of the sleeve 88. Rotation of saidsleeve, as will be apparen procures advance or retraction of thethreaded rod therein and accordingly shifts the position of the carriage6 relative to the carriage advancing mechanism. A set screw I92 whichextends through a cap I98 carried by the housing engages the shaft I88to prevent unintended rotation thereof.

Assuming the parts are in the position shown in the flgures, theworkhead is in its advanced position at the completion of the forwardfeeding movement between the grinding wheel and the workpiece, theworkholding member is being rotated by the motor l8, and the grindingwheel is in contact with the workpiece therein for completing thegrinding operation. The rotation of the work-supporting spindle 8procures a slow turning movement of the star wheel which, after apredetermined period, shifts the plunger I8I, thereby to release thevalve. I28 from the latch I25, said valve then being automaticallyshifted to the right to supply fluid under pressure to the upper end ofthe work-feeding cylinder to retract the workpiece from operativeengagement with the grinding wheel. Said valve also, upon movement tothe right, directs fluid under pressure to the right hand ends of theclutch and brake cylinders so that, as the workpiece is withdrawn fromthe grinding wheel, the driving motor is disconnected from thework-supporting spindle 9, and the latter is brought to rest by thebrake mechanism. The machine come; to rest with the workhead at theright hand end of its movement in which position the workpiece is spacedfrom the grinding wheel.

With the workhead in this right hand position, the lever 40 is manuallyoscillated to admit fluid under pressure to the right hand end of thechuck actuating cylinder for opening the jaws of the chuck to permitremoval of the finished workpiece and the substitution of an ungroundworkpiece therein. The lever 40 is then again actuated for directingfluid under pressure to the left hand end of the chuck controllingcylinder, thereby clamping the unground workpiece in said workholder. Agrinding operation is then procured on the unground workpiece by rockingmovement of the lever I88 which shifts the control valve I28 tothe leftinto the position shown, thereby procuring rotation of thework-supporting member and advance of the workpiece toward the grindingwheel. The work-supporting member then advances rapidly toward the wheeluntil the workpiece is substantially in engagement with said wheel, whenthe rate of movesurface on said workpiece. After an interval, the

star wheel which is rotated from the work-sup- ,porting spindle againprocures shifting move-.

ment of the valve I23 to the right and the abovedescribed operation isrepeated.

I claim,

1. In a grinding machine, a grinding wheel and a workholding member,means for rotating said member, clutch and brake mechanisms between saidrotating means and said workholding member, fluid pressure means foractuating said clutch and brake mechanisms, and means responsive to therotation of said workholding member for controlling the admission andexhaust of fluid under pressure to said fluid pressure means.

2. In a grinding machine, a grinding membe a work-supporting member,means for rotating said work-supporting member, a carriage on which oneof said membersf'is mounted, means to actuate said carriage foradvancing said members into operative position and for a relativefeeding movement between said members, said actuating means alsoprocuring a subsequent retraction of said members, and means responsiveto the rotation of said workholding member to. procure the retraction ofsaid carriage for separating the grinding member from a workpiececarried by the work-supporting member.

3. In a grinding machine, a grinding member,

a workholding member, means for rotating said workholding member, acarriage on which one of said members is mounted, fluid pressure meansfor moving said carriage, and means responsive to the rotation of theworkholding member to control the admission and exhaust of fluid underpressure to said fluid pressure means.

4. In a grinding machine, a grinding member and a workholding member, acarriage on which one of said members is mounted, said carriage havingan inoperative position and an operative position, fluid pressureactuated means to procure movement of said carriage into operativeposition, means responsive to movement of said fluid pressure actuatedmeans to reduce the rate of movement of said carriage as the latterapproaches operative position, and means for procuring a subsequentfeeding movement of the carriage at a continuously changing rate inresponse to the operation of said fluid pressure ac-v tuated means.

5. In a grinding machine, a grinding member and a workholding member, acarriage on which one of said members is mounted, said carriage havingan inoperative position and-an operative position, fluid pressureactuated means to procure movementof said carriage into operativeposition, and means responsive to movement of said fluid pressureactuated means to reduce the rate of movement of said carriage as thelatter approaches operative position, said fluid pressure actuated meansthereafter procuring a slow feeding movement of the carriage at acontinuously decreasing rate.

6. In a grinding machine, a grinding member and a workholding member, acarriage on which one of said members is mounted, fluid pressureactuated means including a cylinder and'piston, and means providing aconnection between said fluid pressure means and the carriage andresponsive to a uniform movement of said fluid pressure actuated meansto procure a movement of said carriage at a continuously changing rate.

'7. In a grinding machine, a grinding member and a workholding member, acarriage on which one of said members is mounted, fluid pressureactuated means, means responsive to a uniform movement of said fluidpressure actuated means to procure a movement of said carriage at acontinuously changing rate", and means to procure a change in the rateof movementof said fluid pressure actuated means during the operationthereof.

8. In a grinding machine, a grinding member and a workholding member, acarriage on which one of said members is mounted, fluid pressureactuated means, means responsive to a uniform movement of said fluidpressure actuated means to procure a movement of said carriage at acontinuously changing rate, and means operable in response to themovement of said fluid pressure means to procure a change in the rate ofmovement of said fluid pressure actuated means during the operationthereof.

9. In a grinding machine, a grinding member workpiece.

10. In a grinding machine,'a grinding member and a work-supportingmember, means for m-' tating a workpiece in said work-supporting member,a carriage on which one of said members is mounted, hydraulicallyactuated means to procure a movement of said carriage for a relativefeeding movement between said grinding member and the workpiece in saidwork-supporting member, and means responsive to the rotation of theworkpiece in the work-supporting member for procuring a retraction ofthe carriage and a cessation of rotation of the workpiece.

11. In a-grinding machine, a grinding member and a work-supportingmember, a carriage on which one of said members is mounted, andhydraulically actuated means for procuring movement of said carriage forarelative feeding movement between said grinding member and a work piecein said work-supporting member, said means including a cylinder andpiston, a rack on-one of said parts, a pinion engaging said rack, andmeans providing a connection between said 'pinion and carriage andresponsive to rotation of said pinion for. procuring movement of saidcarriage at a constantly changing rate when the pinion is rotated at auniform rate.-

WALTER D. ARCHEA.

